Pocket filter assemblies are useful for many applications in which a gas such as air must be filtered. In these types of filters, a number of pockets made of a filter material and having a wide open end or mouth are mounted within a rectangular holding frame. Air or another gas to be filtered flows into the open end and passes through the filter material of the pocket. Particulates in the gas are trapped in the filter material. Spacers are provided within each pocket to keep each pocket from ballooning into the adjacent pockets, which would reduce the surface area available for filtering the gas.
An exemplary pocket filter assembly is disclosed in U.S. Pat. No. 4,056,375, the disclosure of which is incorporated by reference herein. See also FIG. 1. This filter requires a significant amount of work to assemble, since the spacers must be individually assembled into a tubular form and then must be secured to the pocket by stitching, welding, or cementing.